W124 300D temp skyrockets within 2 blocks - PeachParts Mercedes-Benz Forum

dancenplanet · #1 05-09-2008, 02:24 PM

I have a W124 1993 300D 2.5 turbo. I just replaced the water outlet ... thing because it had developed a hole and was leaking coolant everywhere. The repair was a success ... sort of. I refilled the coolant reservoir and took for a test drive. There is no more leak, but the temperature shoots up to 110 within just a couple of blocks. My coolant was green, now its water, but thanks to this forum, I plan to de-oil, flush with water, acid flush, remove block plug, water flush x5, and add the MB coolant. But before I do that I'm wondering if there is a way to test the water pump. It seems to me, unless the cooling system is full of sludge, which it doesn't seem to be since water flows through it clearly, it seems to me I should be able to go more than a couple blocks before over heating provided the water pump is working. When I drove it I ran the defrost to try to get water through the heater core. But even though the temp was off the charts, the defrost was still cold. Is it possible that the leak (and running dangerously low on coolant) caused damage to the water pump? How can I test it?

Thanks
Chip

MattBelliveau · #2 05-09-2008, 02:54 PM

I might try pulling the thermostat and see if you get the same results. That would rule out that being the problem. When my water pump failed (last week, by the way), it was dumping coolant out of the pump itself (they have weep holes). Any funny noises coming from that area?

vstech · #3 05-09-2008, 03:01 PM

while it's unlikely that a leak damaged the water pump, you may have damaged your head... does pressure build up in the system rapidly too? does the pressure go away when the motor cools down? any signs of oil in water or vice versa?

vstech · #4 05-09-2008, 03:02 PM

oh, and cold heater leads me to think there is not enough water in your block... or you may have a failed temp sending unit...

dancenplanet · #5 05-09-2008, 03:10 PM

would oil in the water be real obvious? I noticed a slight rainbow glisten on the water after re-draining, but I assumed that was just from the pan I drained into (same pan to drain oil for oil changes).

The car does "pulse" when even acceleration is applied. Would/could that be related?

I'm rather new to auto maintenance (my usual excuse: My dad was a layer) so I'm still learning where/what everything is, can you point me to the water pump and the thermostat.

dancenplanet · #6 05-09-2008, 03:12 PM

I didn't notice the pressure being any different then usual (its always been kinda wonky). I am going to go check the water level again, add as necessary and take another drive. I pay more attention to the pressure this time.

dancenplanet · #7 05-09-2008, 03:37 PM

So, water level was low (that's to be expected after draining and refilling right?) so I topped it off and went for another drive (these drives might be too short, only going 5 blocks total). The pressure stays at 3 when accelerating, between 1 and 2 when coasting and idling. The temp stayed cooler this time (a little over 100c, previously it was 120c, not 110c as I had stated before.) The defrost still never got even warm.

The pulsing thing I'm fairly sure is my trans screaming for a flush and new filter. It seems to subside after a shift, only to return as the RPM's ramp up to another shift.

Any further thoughts? Is the water pump connected to the large flywheel at the top of the S-belt on the drivers side? Is the thermostat near the water pump? I have an E-class Bible, but it's not much help on the 602 engine.

mkrazy1 · #8 05-09-2008, 04:48 PM

By pressure, I believe vstech was referring to radiator pressure, and it sounds like you are just looking at the oil pressure. With the engine off and cool, check the upper radiator hose. You should be able to squeeze it with there being no pressure in it. Start the engine and see how quickly the radiator hose builds up pressure to where you can't squeeze it. It the head gasket has blown, it will build up pressure pretty quickly.

dancenplanet · #9 05-09-2008, 05:00 PM

Ohhhh. See, I told you I don't know much about auto maintenance. I know the hose is soft when the engine is cold. I haven't checked it when the engine is running, or even afterwards.

I'll check that tonight.

Phil · #10 05-09-2008, 05:35 PM

Here is a hint I have used on some cars. Disconnect the upper radiator hose from the radiator side and pour water or coolant in the end of the hose. On some cars the water doesn't get into the block until the water is hot and the thermostat opens so this method puts water on the other side of the thermostat so it gets into the block and head of the engine. I had to do it this way on my car.

dancenplanet · #11 05-09-2008, 06:20 PM

Thanks Phil, I'll try that too.

diesel friend · #12 05-09-2008, 08:36 PM

I second what Phil said. I would say that you have trapped air in the cooling system and therefore getting the high temperature. With the engine being cold I recommend you slacken off the hose clamps on the top rad hose. Remove the hose at the end pointing to the engine, twist it around a bit and fill the rad, then do the same with other end of the hose get coolant into the engine. Install the hose and tighten the clamps. Remove the cap from the coolant reservoir and start the engine and let it idle. Watch the temp gauge and also the resevoir.
At one point you will most likely see air burbing out. After this put the cap back one and take the car for a test drive. If everything is normal temp. should be about 80 Degr. F. All this with the thermostat in place. This procedure worked for me on 2.5 liter diesel non-turbo.

Brian Carlton · #13 05-09-2008, 08:45 PM

Quote:

Originally Posted by Phil

Here is a hint I have used on some cars. Disconnect the upper radiator hose from the radiator side and pour water or coolant in the end of the hose. On some cars the water doesn't get into the block until the water is hot and the thermostat opens so this method puts water on the other side of the thermostat so it gets into the block and head of the engine. I had to do it this way on my car.

Exactly.

The cylinder head cannot fill with coolant because the thermostat is closed. The coolant fills the radiator and the lower hose and comes to a dead stop at the thermostat.

The only way to get coolant into the head is via the upper hose. You've got to remove the upper hose and fill the head with coolant which will eliminate the problem.

dancenplanet · #14 05-09-2008, 11:59 PM

Success!!! That did it. I did as Phil & Diesel Friend suggested, filled the head and the radiator from the radiator hose. Then I let it idle for a few minutes with the reservoir cap removed, but I only saw bubbles while revving the engine.

I took it out for a longer drive this time and it only went above 80c while it was idling (I was adjusting the new headlight lens).

Thanks everyone for the suggestions. If it wasn't for forums like this, I'd probably be taking my cars to a mechanic even to check the tire pressure.